The invention relates to a printing press and more specifically to a web feed rotary press, comprising at least one impression cylinder arranged to cooperate with at least one transfer cylinder for transfer of the printing image to the web to be printed with an apparatus for preventing soiling of printing material.
In arrangements of this type it frequently occurs that the side of the web engaging the impression cylinder carries a fresh printed image which has not had sufficient opportunity to dry so that there is a risk of the ink soiling the impression cylinder. Experience has shown that solvent contained in the ink collects on the impression cylinder and softens and detaches more and more ink from the printed image on the web. The consequence of this is that the ink deposited on the impression cylinder will be transferred back onto the web in an undesired manner with the result that the web will be soiled and has to be thrown away as reject material. So far it has thus been necessary to halt the press from the to time in order to clean the impression cylinder by hand with a rag. This was not only an awkward operation to perform but furthermore did not prevent any further fouling of the impression cylinder.